IMO Hockey is the best sport in HD. with the wider screen shots you get to see everything from the blue line to the boards behind the net, you can see teams setting up the offense and see whats happening, plus the puck is very easy to follow (no need to light it blue like NBC did years ago).
The other sports are great with the resolution and clarity, but the wider screen doesnt actually do things to benefit the TV coverage of showing the sport... take football for example, they like to center the coverage on the Line of Scrimmage, you get a bit more of the defense, but you also get another 5-10 yards behind the running back... Very nice crisp clear green grass, maybe a logo on the field, but nothing to add to the game.